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A Simple Overview of How Different Autoclaves Work

An autoclave, also called a steam sterilizer, works on the principles of steam, temperature, and pressure.  The forced steam in the chamber penetrates all surfaces of the gear inside the machine.

Also, autoclaves use steam under pressure because the water boils at a higher temperature when pressurized.  The steam carries more heat this way and kills the bugs more effectively.  This has been proven to be the most effective way to kill all the microorganisms on contaminated items.

This article is going to cover how different sterilizers accomplish the process in a general sort of way.

General Steps for Autoclaving

This description all depends on the type of sterilizer you are using.  Water is placed into the device or machine reservoir to the fill line.  The chamber door is closed and secured either with thumb screws, a secured handle, or an automatic door lock.

Next, for an automatic sterilizer, the right cycle is chosen and the start button is pressed.  Automatic ones have their temperature and pressure controlled by internal computers during the cycle.  Their doors lock for safety when pressurized.

For a manual autoclave, timer dials are turned.  An internal heating element begins the work of turning the water to steam.  Monitors and gauges are used to keep the correct pressure and temperature in their correct ranges.

There are generally two main steam sterilization cycle types across the different models of autoclave machines.  One method of sterilization is termed “gravity” (steam enters under the usual atmosphere and replaces the air with a bottom drain).  The other is vacuum or “prevac“, which is steam under pressure and more effective.

Gravity is used for gear that cannot handle being pressurized.  Many automated table top autoclaves allow for choosing between the two cycles.  Many offices need both of these cycles based on the gear.

There are even a couple of inexpensive stove top autoclave models that work with a heating element combined with the stove to create the pressure.  These are mainly for decontamination of things like animal grooming instruments.  They look and act like pressure cookers, to get an idea.

As operators of autoclaves, we must know what cycles our instruments and gear can handle.  Based on this, we choose the correct autoclaves for our offices.  We run the correct cycle for the correct time to ensure sterilization takes place.  Every part of the process is needed.

During the steam cycle, all the microscopic surfaces are penetrated.  This is vital because the microbes fill every tiny area.  This is why we decontaminate the instruments vigorously before preparing them to be autoclaved.

After the cycle is run in the machine, a drying period must take place.  The instruments have been wrapped or are in pouches, usually.

Again, different steam sterilizers do this drying differently.  High end machines might have a built in drying cycle, which can be quick.  Others must have the door cracked open to vent for a correct time. These are the main ways.

If they are not correctly dried, the standing moisture can contaminate the gear with microbes.  This is worst case (along with a failed cycle) as it can be undetected and a danger to patients and workers.

That is why I am happy to write articles like this as guides and warnings.  We must pay attention to detail with decontamination.  It can be very harmful or deadly to work with dirty gear.  Our education about the specifics is necessary.

Thanks for reading.  Feel free to leave a question in the comments and I’ll add to this or write something else!